The present invention relates to a device for measuring the to displacement travel of a hydraulic displacement mechanism for the blades of the impeller of an axial-flow fan.
Modern axial-flow fans are regulatable work machines that convert mechanical energy into kinetic energy. The regulation of the axial-flow fans is effected by the speed or the angle of the blade. If the position of the blade is to be altered during operation, the blade must be secured to a supported shaft via the spindle. The alteration of the blade position is generally effected hydraulically. For this purpose, a hydraulic displacement mechanism is installed on the impeller of the axial-flow fan. Such a displacement mechanism is essentially comprised of a hydraulic displacement cylinder arrangement that rotates with the speed of the fan, and a non-rotating oil transfer element to which the oil supply lines are connected.
The position of the blades of the axial-flow fan correspond to a specific position of the displacement cylinder arrangement. This position is indicated externally of the fan housing, via a position indicator that is mechanically connected to the displaceable component of the displacement cylinder arrangement, and can also be conveyed to an observation means by means of an attached angle coder. Such a mechanical arrangement for indicating position is relatively imprecise. Furthermore, due to the mechanical connection wear in the connecting parts must be taken into consideration.
The present invention deals with the problem of providing an advantageous device for measuring the displacement travel of the hydraulic displacement mechanism of axial-low fans. Such a device must be suitable for the measuring inset on the blade adjustment device in the hub space of the axial-flow fan.
It is an object of the present invention to provide a displacement-measuring device for a device of the aforementioned general type that operates with relatively great precision, delivers absolute values, and is free of wear.